For many years, whalers and field observers did not distinguish between Bryde's and sei whales in their records. Now, however, whales of the 2 species can be, and are being, distinguished even at sea. Bryde's whales usually have 3 prominent ridges on the rostrum (other rorquals generally have only 1). This is perhaps the best characteristic to use, although one is best advised to consider information on other characters as well. The Bryde's whale's dorsal fin is tall and falcate and generally rises abruptly out of the back, a feature that will help distinguish this species (and sei whales) from fin whales, in which the dorsal fin rises at a relatively shallow angle from the back. The height of the blow is variable. Bryde's whales often exhale underwater, then surface with little or no blow.

Bryde's whales can be easily confused with sei whales. The presence of 3 head ridges confirms a whale's identity as a Bryde's whale (however, be aware that rippling water on the head of other species can be mistaken for accessory head ridges). Fin and minke whales can also cause some confusion; size (fin whales are larger and minke whales smaller), head shape, and coloration differences are the best characteristics to use.

Size

Adults can be up to 15.5 m long; newborns are about 4 m. Maximum weight is about 20 to 25 t. A smaller form has been described from some areas.

GeographicalDistribution

Bryde's whales are creatures of the tropical and subtropical zones and generally do not move poleward of 40° in either hemisphere. They are found both offshore and near the coast in many areas. Whales of this species are not known to make extensive north to south migrations, though short migrations have been documented. Resident populations may be common in certain areas, such as the Gulf of California.

BiologyandBehaviour

Although generally seen alone or in pairs, Bryde's whales do aggregate into groups of 10 to 20 on feeding grounds.

Unlike other rorquals, the tropical Bryde's whale does not have a well-defined breeding season in most areas, and births can occur throughout the year.

Bryde's whales are primarily fish eaters, but they also take invertebrates. They are very active lunge feeders, often changing direction abruptly when going after mobile fish prey.

Exploitation

The history of whaling for Bryde's and sei whales is nearly impossible to separate, because these species were not consistently distinguished until recently. The Bryde's whale is one of the few great whales not listed as endangered.